Boiler with multiple superheaters



26, 1933. G P. JACKSON 1,941,354

BOILER WITH MULTIPLE SUPERHEATERS I Filed may 1, 1931 2 Smets-sheet 1 Alf? HEATER j] REHEA TER BY Y g ATToR l-:Ys

Dec. 26, 1933. G. P. JACKSON 1,941,354

l I BOILER WITH MULTIPLE SUFERHEATERS Filed May l, 195i 2 Sheets-Sheet 2 HEHE/177:' R

Patented Dec. 26, 1933 l 1,941,354 `oI'LER WITH MUL'rIiLnsUPERHEA'rERsl Y George P. Jackson, Flushing, N. Y., assignor to International Combustion Engineering Corporation, New York, N. Y., a corporation of Dela- 3 Claims.

This invention relates to boilers with multiple superheaters and is particularly concerned with the type of boilers which are adapted to the burning of pulverized coal and in which relatively high superheat is desirable.

Generally considered, the invention has in View increased efliciency as well as flexibility of control with respect to the temperature and the like of the superheated steam. f

The general nature of this invention, as well as the objects andadvantages above-noted, and

others which will occur to those skilled in the art, will be more apparent from the consideration of the following discussion making reference to the accompanying drawings n which Figure 1 is a vertical sectional View through a furnace-shaped boiler in which the present invention is embodied; and

Figure 2 is a vertical sectional view taken substantially as indicated by the section line 2 2 applied to Figure 1.

In Figurel, it will be seen, the combustion space of the boiler is substantially deiined, in its four Vertical walls, by the tubes 3, these tubes, of course, being subjected to radiant heat.

In accordance with the present invention, -I have arranged or disposed superheater elements 4 in a portion ofthe furnace oit-take -5 adjacent to the combustion space itself. These superheater tubes 4 constitute the elements preferably comprising va duct 6 controlled by a damper 7. i

In the upper portion of the furnace-shaped boiler, most clearly illustrated in Figure 1, I have arranged a secondary i or second-stage superheater comprising tubes 8. This superheater is preferably screened somewhat from the radiant `heat of the combustion chamber as byvmeans of convection or water circulation tubes 9 extended from the steam and water drum 10 below the tubes 8 to the opposite side of the chamber. This secondary heater, it will be understood, is preferably arranged for serialv connection with the tubes 4 of the primary superheater, the relative Application May 1, 1931. Serial No. 534,269

disposition of the two heaters being Vsuch as to aord very high delivered superheated steam tem;-

peratures. The reason for this, of course, is partly due to the multiple superheater arrangement, but results, more especially, from the fact` that the secondary heater is disposed at a point in which gases of relatively Vhigh temperature contact therewith, as compared to the gases in the off-take. v

Still further, the present invention includes a re-heater 11 arranged in the off-takebeyond the arrangement further being advantageous in` affording maximum eiciency from the standpoint of heat losses from the installation,'as' by convection or radiation. Additionally, the serial arrangement (speaking with reference to the contact of gases or products of combustiomof the secondary superheater, the primary superheater, re-heater, and an air heater, is generally advantageous from the standpoint of yutilization of gas temperature and specically advantageous in eiecting economies in an installation where relatively high superheat is desired. This arrangement, it might also be noted, provides for a high superheatwith a minimurnof superheater' elements or tubes disposed within the combustion chamber, i. e., in a very high temperature zone. In this way, replacements, repairs, or the like are considerably reduced in an installation designed to produce superheat in the temperature ranges here contemplated. Still further, serial arrangement of the superheaters and the like,

particularly in the manner herein disclosed,

efliciently reduces gas temperatures tothe desired low point before exit.

Another important feature of this ,invention resides in the disposition of the by-pass or control means, for the gases passing ythrougn the superheater, in associationl with the tubes of the iirst stage which are arranged in the off-take.

disposed in association with a superheater arranged in the combustion chamber itself. For example, in. a construction such as illustrated in Figure 1, in which shielding tubes or screening elements are employed and disposed below the secondary superheater, accurate control for the gases passing over the tubes is very diicult to obtain if the control elements be associated with the tubes of this secondary heater. This will be apparent when itis considered that this secondary heater is disposed Within the furnace-shaped boiler itself, which, of course, is of relatively large cross sectional area. In addition, the disposition of adjustable control means in association with a superheater arranged within the combustion chamber, at times produces uneven or irregular gas flow with respect to the'superheater screening tubes.

In any case, I have found that much more accurate control may be ,obtained by the arrangement herein disclosed, i. e., an arrangement iny which the control is afforded by the use of bypass means associated with a primary' superheater disposed in the off-take.

The operation of the by-pass duct, clearly illustrated in Figure 2, involves manipulation of the damper 7 either to provide substantially free and unobstructed flow through the duct (resulting in relatively small flow through the spaced groups of primary superheater tubes) or to materially restrict flow through the duct 6 and thus divert additional products through the tubes of the spaced groups. The damper 7, of course, may be controlled as by means of a thermostat associated with a superheater delivery line, preferably from the second stage, or, if desired, this damper '7 may be arranged for manual operation iin accordance with various steaming and other operating or load conditions.

In accordance with the foregoing, uniform superheat is provided for under varying load and furnace operating conditions, it being apparent that` in addition to this, the arrangement provides for maximum flexibility to meet varying load. or operating conditions which, at times may require different degrees of superheat.

What I claim is:

l1. In combination with a high temperature furnace-shaped boiler; an off-take at pne side thereof; a primary superheater in the off-take, said superheater including sets of tubes extended transversely of the direction of gas ow through the off-take and substantially the entire distance across the off-take from side to side thereof whereby to provide for the passage therethrough of substantially all the gases flowing in the off-take, said superheater further-including additional sets of. tubes extended transverselyl of the direction of flow through the off-take, the additional sets being disposed beyond the sets first mentioned with respect to the direction of gas llow and being spaced from each other; acljustable gasby-pass means in a space between the said additional sets of tubes; and a secondary superheater extended across the top of the boiler.

2. In a high temperature boiler installation, boiler tubes substantially wholly defining a combustion chamber to receive heat from the fuel and flame stream by radiation, an oit-take from said chamber, a primary superheater in an advance portion of the off-take, a secondary superheater disposed in the combustion chamber in a region thereofadjacent to the point of communication of said off-take, saidprimary and secondary superheaters being serially interconnected, in which construction, since the boiler tubes receive heat almost wholly by radiation and since steam flowing through the secondary superheaterv is at relatively high temperature,

the orf-take gases passing over the primaryl superheater are also at relatively high temperature, the said primary superheater being divided into a plurality of sections serially arranged in the off-take, together with adjustable gas bypass means in the off-take associated with a section of the primary superheater remote from the point of communication of the off-take with the combustion chamber, there being tubes of an advance section` of the primary superheater, disposed ingas-ow alignment with the gas by-pass means, whereby provision is made for 'the delivery of relatively highly superheated steam from said secondary superheater under temperaturev control` byv virtueV of said by-pass without however, means to excessive temperatures.

3. In a high temperature boiler installation;`

boiler tubes substantially wholly defining a combustion chamber to receive heat from the fuel and flame stream by radiation; an off-take from said chamber; a primary superheater in an adv subjecting the adjustable by-pass` vance portion of the off-take; a secondary superva plurality of sections serially arranged-,iii the off-take; adjustable gas byr-pass meansinthe olftake associated with a. section of the primary superheater remote front the point of: communication of the olf-take with the combustion chamber; there being tubes; ofan advance section-of the primary superheater disposed in gas-ow alignment with the gas by-pass means, whereby provision is made for the delivery of relativeiy high- 1y superheated steam from said secondary superheater under temperature control by virtue of said by-pass Without, however, subjecting the adjustable by-pass 'means to excessive temperatures; an air heater disposed in said olf-take beyond said primary superheater; and a iiuid carrying heat absorber in the off-take interposed between the primary superheater and the air heater in gas-flow alignment with said gas bypass means, whereby, even when the gas by-pass means is relatively widely opened, the gases pass-Y ing through the by-pass means are reduced in temperature before passage thereof through the air heater.

' GEORGE P. JACKSON. 

